A new study conducted at the Piglet Nutrition and Cognition Lab at the University of Illinois suggests that prebiotics (small and indigestible fiber molecules that promote the growth of good bacteria in the gut of babies), can improve memory and exploratory behavior when included in infant formula.
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Breast milk is a natural source of prebiotics. Although American parents are encouraged to offer breast milk to newborns, breastfeeding is often difficult or impossible for many mothers. Fortunately, with the help of researchers at University of Illinois, modern infant formulas are getting closer to the real thing.
When we provide prebiotics in formula, our results confirm that we can not only benefit gut health, which is known, but we can also influence brain development."
Ryan Dilger, Associate Professor in the Department of Animal Sciences, Division of Nutritional Sciences, and Neuroscience Program at the University of Illinois
According to him, by enhancing colonic bacteria, the researchers were able to alter the way the piglets learned and remembered.
As the digestive systems, behavioral responses, and brain development of piglets are remarkably similar to human infants, they are widely considered a more informative model for human infants when compared to mice or rats. Thus, researchers are increasingly turning to piglets to test hypotheses in pre-clinical trials related to human health, mainly in the context of brain development and gut microbes..
Stephen Fleming, lead author of the study and a doctoral student in the Neuroscience Program at the University of Illinois explained that prior trials on rodents that focused on the gut-brain axis in humans has shown a connection, and the current study intended to check if the connections exist in an animal model that is a lot closer to human infants and if it is possible to tease out possible mechanisms.
The findings of a study on piglets conducted by Dilger and his team in early 2016 indicated that a combination of innovative formula components, including prebiotics, might play a role in behavior and brain development. In the present study, the team focuses solely on the impacts of prebiotics.
From the second day of birth, the piglets were provided with an infant formula based on cow’s milk, which is supplemented with polydextrose (PDX), a synthetic carbohydrate with prebiotic activity, and galactooligosaccharide (GOS), a naturally occurring prebiotic.
When they were 25 days old, the piglets underwent various learning, memory, and stress tests. Blood, brain, and intestinal tissues were acquired after 33 days for analysis.
In the learning and memory tests, the piglets got a chance to play with dog toys: one they'd already seen and one brand new toy. Piglets spending more time with the new toy was an indication that they identified it as a new one and preferred it. This "novel object recognition" test is an enhanced model of classic maze tests that are commonly used in rodent studies.
When compared with piglets that are not fed with prebiotic supplements, the piglets fed with PDX and GOS spent more time playing with new objects. The preference for new objects, signifies healthy brain development and points toward positive development of learning and memory.
When prebiotics work properly, good bacteria increase in abundance, and can be confirmed by the presence of metabolic end-products-volatile fatty acids (VFAs) - excreted by bacteria at the time of digestion of prebiotic fibers.
VFA concentrations in the colon, blood, and brain were altered in piglets that received PDX and GOS, when compared with control pigs. According to recent evidence, bacterial VFAs could enter the blood and travel to the brain, possibly affecting mood and behavior.
We found that, yes, VFAs are absorbed in the blood of pigs that were fed PDX/GOS. And, yes, they do get into the brain. But when we looked at the relationship between these VFAs and the results of our behavior tests, there did not appear to be a clear connection."
Stephen Fleming, lead author of the study and a Doctoral student in the Neuroscience Program at the University of Illinois
The researchers also saw a decrease in the level of serotonin in the piglet brains after they were fed the prebiotic. Despite this, the piglets did not show any greater anxiety than control pigs during a stress test or poorer performance when given a learning and memory test.
According to the researchers, prebiotics may also alter the levels of tryptophan (serotonin's amino acid precursor), but this could not be confirmed by the study.
"There are so many ways we can alter the composition of the microbiota and they can have very strong benefits. Promoting good 'gut health' remains a strong focus in the field of nutrition," said Ryan Dilger, associate professor in the Department of Animal Sciences, Division of Nutritional Sciences, and Neuroscience Program.